CN203310903U

CN203310903U - Transformer iron core earth current online monitor

Info

Publication number: CN203310903U
Application number: CN2013202614386U
Authority: CN
Inventors: 林华斌
Original assignee: NINGBO QIXIN ELECTRICAL TECHNOLOGY Co Ltd
Current assignee: NINGBO QIXIN ELECTRICAL TECHNOLOGY Co Ltd
Priority date: 2013-05-13
Filing date: 2013-05-13
Publication date: 2013-11-27
Anticipated expiration: 2023-05-13

Abstract

The utility model discloses a transformer iron core earth current online monitor. The online monitor comprises a single-chip microcomputer and an A/D conversion circuit which is electrically connected with the single-chip microcomputer, wherein the A/D conversion circuit is connected to a current sensor through an automatic range converting and filter circuit; the current sensor is connected with a transformer iron core earth wire; and the single-chip microcomputer is further electrically connected with a watchdog circuit, an LED digital display and a WIFI wireless measurement and control apparatus. A current transformer that is connected with the transformer iron core earth wire converts iron core earth current signals into digital signals for easy identification via the automatic range converting and filter circuit and the A/D conversion circuit, and then the digital signals are transmitted to the single-chip microcomputer; the single-chip microcomputer uploads alarm signals and the measured data to a controller through the WIFI wireless measurement and control apparatus, and thus real-time continuous online monitoring and alarming of the transformer iron core earth current is realized, and the transformer fault rate is helped to be reduced.

Description

Transformer iron core grounding current on-line monitoring device

Technical field

The utility model relates to the current monitoring technical field, particularly a kind of transformer iron core grounding current on-line monitoring device.

Background technology

Power transformer is one of equipment crucial in electric system, is also the higher link of failure rate in power equipment, and its normal operation is the important guarantee of power system security, reliable, high-quality, economical operation.When power transformer normally moves, iron core must have and only have some reliable grounds, in case when 2 of iron cores or multipoint earthing, in core interior, can produce circulation, cause local overheating, when serious, can cause the iron core localized burn, even make ground lug fusing, cause the iron core electric potential floating, produce discharging fault, the reliability service of serious threat transformer and electrical network, data shows according to the relevent statistics, because of the accident that multipoint earthing of iron core of transformer causes, occupy the 3rd in the total accident of transformer, so the multipoint earthing of iron core of transformer fault can not be ignored.

The means that current operations staff detects iron core grounding current mainly adopt clamp on amperemeter to measure the current data of iron core grounding extension line, but on-the-spot electromagnetic interference (EMI) is large, be difficult to guarantee precision and the accuracy of clamp on amperemeter data, and regular visit can't guarantee to find in time the multipoint earthing of iron core fault.

The utility model content

The purpose of this utility model is for the defect of prior art and deficiency, and a kind of real-time continuous on-line monitoring and warning that can realize transformer iron core grounding current is provided, and is of value to the transformer iron core grounding current on-line monitoring device that reduces the transformer fault rate.

For achieving the above object, the utility model is by the following technical solutions:

Transformer iron core grounding current on-line monitoring device described in the utility model, comprise single-chip microcomputer and the A/D change-over circuit be electrically connected to single-chip microcomputer, described A/D change-over circuit changes by automatic range and filtering circuit is electrically connected to current sensor, described current sensor is electrically connected to the transformer core grounding line, also with watchdog circuit, LED digital indicator, WIFI Radio test and control apparatus, is electrically connected to respectively on described single-chip microcomputer.

Further, described A/D change-over circuit adopts the MAX197 chip.

Further, described automatic range conversion and filtering circuit comprise the signal processing circuit consisted of the difference ratio circuit be connected in parallel, ratio amplifying circuit, and the filtering circuit formed by the high-order active low-pass filter, described signal processing circuit and described filtering circuit are connected in series.

Further, described WIFI Radio test and control apparatus comprises WIFI wireless terminal and WIFI wireless access point device.

Further, also comprise storer, described storer is electrically connected to described single-chip microcomputer.

The beneficial effects of the utility model are: the current transformer be connected with the transformer core grounding line, by the iron core grounding current signal by automatic range conversion and filtering circuit, A/D change-over circuit, be converted to the digital data transmission being convenient to identify to single-chip microcomputer, single-chip microcomputer by the WIFI Radio test and control apparatus by alerting signal and measured data upload to the control personnel, realize real-time continuous on-line monitoring and the warning of transformer iron core grounding current, be of value to the transformer fault rate that reduces.

The accompanying drawing explanation

Fig. 1 is one-piece construction schematic block diagram of the present utility model.

Embodiment

Below in conjunction with accompanying drawing, the utility model is further described.

Transformer iron core grounding current on-line monitoring device as shown in Figure 1, comprise single-chip microcomputer and the A/D change-over circuit be electrically connected to single-chip microcomputer, described A/D change-over circuit changes by automatic range and filtering circuit is connected to current sensor, described current sensor is connected with the transformer core grounding line, also with watchdog circuit, LED digital indicator, WIFI Radio test and control apparatus, is electrically connected respectively on described single-chip microcomputer.The utility model adopts the X25045 watchdog circuit, can guarantee the system reset after program fleet.

The current transformer be connected with the transformer core grounding line, by the iron core grounding current signal by automatic range conversion and filtering circuit, A/D change-over circuit, be converted to the digital data transmission being convenient to identify to single-chip microcomputer, single-chip microcomputer by the WIFI Radio test and control apparatus by alerting signal and measured data upload to the control personnel, realize real-time continuous on-line monitoring and the warning of transformer iron core grounding current, be of value to the transformer fault rate that reduces.

Described A/D change-over circuit adopts the MAX197 chip; MAX197 is a multirange, 12 Bit Data Acquisition Systems; its program control amplifier, Channel-shifted, reference source, clock circuit, A/D and Power Management Unit that acquisition system is required concentrates on a chip; adopt single+5V Power supply, tape jam protection input multiplexer.The MAX197 integrated level is high, switching rate fast (6 microsecond), and cost performance is high.

Described automatic range conversion and filtering circuit comprise by the difference ratio circuit be connected in parallel, the signal processing circuit that the ratio amplifying circuit forms, and the filtering circuit formed by the high-order active low-pass filter, described signal processing circuit and described filtering circuit are connected in series, the difference ratio circuit, under the signal processing circuit that the ratio amplifying circuit forms can guarantee to nonserviceable, core current is during than glitch, and the measurement under normal condition, the MAX274 that the utility model adopts MAXIM company to produce, MAX274 is monolithic integrated active filter, without external capacitor, can effectively reduce the circuit volume, improve circuit performance, adopt MAX274software as higher order filter, plenty of time can be saved, also avoided the people to be miscount, adopt Butterworth8 rank low-pass filter, this wave filter has the amplitude characteristic of maximally-flat in passband, and along with presenting dullness, the frequency rising reduces.

Described WIFI Radio test and control apparatus comprises WIFI wireless terminal and WIFI wireless access point device, and the WiFi wireless terminal is realized data acquisition and the wireless transmission of industrial field device.WiFi wireless network transmissions speed is high, has stronger antijamming capability, is adapted at using in severe industrial environment.

The utility model also comprises storer, and described storer is electrically connected to described single-chip microcomputer, deposits the result of measurement and the time constantly of measuring in storer, as the information back-up data, for post analysis iron core grounding current working condition, providing foundation.

The above is only preferred embodiments of the present utility model, therefore all equivalences of doing according to the described structure of the utility model patent claim, feature and principle change or modify, is included in the utility model patent claim.

Claims

1. transformer iron core grounding current on-line monitoring device, it is characterized in that: comprise single-chip microcomputer and the A/D change-over circuit be electrically connected to single-chip microcomputer, described A/D change-over circuit changes by automatic range and filtering circuit is electrically connected to current sensor, described current sensor is electrically connected to the transformer core grounding line, and described single-chip microcomputer also is connected with watchdog circuit, LED digital indicator, WIFI Radio test and control apparatus respectively.

2. transformer iron core grounding current on-line monitoring device according to claim 1, is characterized in that: described A/D change-over circuit employing MAX197 chip.

3. transformer iron core grounding current on-line monitoring device according to claim 1, it is characterized in that: described automatic range conversion and filtering circuit comprise the signal processing circuit consisted of the difference ratio circuit be connected in parallel, ratio amplifying circuit, and the filtering circuit formed by the high-order active low-pass filter, described signal processing circuit and described filtering circuit are connected in series.

4. transformer iron core grounding current on-line monitoring device according to claim 1, it is characterized in that: described WIFI Radio test and control apparatus comprises WIFI wireless terminal and WIFI wireless access point device.

5. transformer iron core grounding current on-line monitoring device according to claim 1, it is characterized in that: also comprise storer, described storer is electrically connected to described single-chip microcomputer.